The invention relates to a device for conducting research on cell specimens and similar samples, which has a microtiter plate or a similar receptacle device with a plurality of individual containers for cell specimens, and having a measuring device for recording changes in the individual specimens, wherein at least one sensor is provided with each receptacle container.
Various medical-biochemical test procedures can be conducted with the aid of so-called microtiter plates. Microtiter plates have a plurality of receptacle tubes arranged alongside one another, into which the cell specimens, for example a suspension of metastatic cells, are introduced. Subsequently, an indicator solution, for example a fluorescent dye, is added. To study whether certain substances can influence the metastatic cells, especially kill them, various cytotoxic substances are added. The introduction of cell specimens, indicator solution and medications takes place in a sampling technique conducted by means of an automatic device. Cell changes can be detected in a fluoroscopic procedure or with the aid of a spectrometer.
Besides chemotherapy testing, microtiter plates can also be studied for research on cancer cells as to their metastatic tendency. In this case, a test substrate consisting of a layer of cells or embryonal HM-cell cultures or a collagen matrix, is positioned in the containers upon which the metastasic cells are then placed. According to the degree of change, a measure for the invasion index or the metastatic index can be derived. This procedure, in which biological layers of another substance are more or less influenced, is also called biocorrosion. Studies, for example of plastics for biocompatibility, are also possible therewith. That is, it is studied whether or not cells penetrate into the plastic under investigation.
With these various studies, a fluoroscopy process is usually provided for the evaluation, with measurement assessment by a microplate reader or by means of a spectrometer. Consequently, on the one hand, a not inconsiderable equipment expenditure is necessary for the functional suitability of the overall device, and on the other hand, the measurement assessments do not in all cases provide information to the extent desired, for example even about the running reaction process. It is furthermore disadvantageous that with commercially available microtiter plates, comparatively large sample amounts are necessary. Appropriate sample amounts, however, are not always available, for example of biopsy material.
A device is known from German published patent application DE 39 15 920 A, which has a micromechanical structure with a plurality of depressions situated in a block of semiconductor material as sample containers The sample containers are installed in the block through chemical etching. These receptacles are nonetheless suited only for very small sample amounts. Moreover, special sampling facilities are necessary.
A microelectronic device is known from published International (PCT) application WO-A-9601836, which likewise has a plurality of individual containers as sample containers, which as microcontainers are suited exclusively for accommodating the smallest sample amounts. The electrodes provided in the microcontainers can basically only be used for conductivity measurements. This device is equipped for DNA examination, and among others, no physiological measurements on living cells can be conducted with it.
An object of the present invention is to create a device of the type mentioned at the beginning which makes possible a plurality of different examinations at a reduced overall cost, including continuous monitoring of a reaction process, and which is also simpler to handle.
For accomplishing this objective, it is proposed in accordance with the invention that the measurement facility has semiconductor sensors with at least one interdigital condenser situated on one or more substrate plates, and that a honeycomb-like tube structure consisting of a bottomless upper part of a commercially available microtiter plate is mounted on the semiconductor substrate plate and tightly connected with the substrate plate.
By using a microtiter plate xe2x80x9cupper part,xe2x80x9d the facilities previously used in connection with microtiter plates, especially the automatic sampling machine, can continue to be used. Moreover, correspondingly more test fluid can be accommodated according to need. Semiconductor sensors offer a plurality of different measuring possibilities so that appropriate sensors can be provided according to the application and measuring object. Such sensors can also be realized in the smallest designs, so that it is correspondingly possible to work with even the smallest sample amounts. Thus, studies on cells, for example, are also still possible even if these can only be taken from a patient in a very small amount, for example as biopsy material. It is also advantageous that the receptacle device with the individual containers and the practically integral measuring facility form a complete functional unit and also a compact construction unit, which is also simpler to handle. The sensors are hereby respectively part of the measuring chamber, so that these no longer need to be brought into connection with a separate measurement facility for evaluation. Also advantageous is that a measurement during a running reaction process, and moreover measurement simultaneously with all individual containers, is possible.
With the aid of interdigital condensers as sensors, measurements of changes in shape of the cells can in particular be conducted, and furthermore, impedance and capacitance changes of the cell membrane can be measured. Antibodies which accumulate on cells can also be detected, since they change the dielectric constants in the area of the interdigital structure. Preferably the electrodes of the interdigital condensers intermesh in pairs with one another.
Expediently, several, preferably different sized, interdigital condensers are provided. These have a distinct sensitivity, so that accordingly a larger measuring area is covered, and a higher resolution in the individual measurement areas is made possible.
Preferably, it is provided that the sensors, at least for some receptacles, are situated on a common wafer-like semiconductor substrate plate. On such a semiconductor substrate plate, a plurality of sensors can be accommodated by known manufacturing technology in a narrow space, so that a precondition for an especially compact design of the device is thereby present. The semiconductor substrate plate with the individual sensors hereby practically forms a measurement structure allocated to the receptacles.
A preferred embodiment provides that the device have at least one semiconductor substrate plate with a plurality of small bowl-shaped receiving depressions situated within it as containers, and that the sensors allocated to the depressions, overall forming a measurement structure, be a component of the substrate plate.
It is also possible with this device, in particular, to work with the smallest sample amounts. Moreover, such a device can be manufactured completely with semiconductor technology. Furthermore, an extremely compact construction is realizable therewith.
According to a refinement of the invention, there can also be provided herein, in the area of an individual container or a receptacle depression, several, preferably different, sensors, in particular as a sensor array, so that different parameters can be recorded simultaneously during the examination. Such a sensor array can be manufactured especially economically as an integrated circuit, and makes possible the measurement of different chemical or biological substances on the most constricted space.
Depending on the object of the investigation, there also exists the possibility, however, of arranging different sensors with the individual receptacles, wherein one or more receptacles have the same sensors in their respective area and different types of sensors are provided with other receptacles or groups of receptacles.
The measurement facility with its measuring structure is expediently arranged on the underside of the receptacle device, and each receptacle carries at least one sensor in the floor and/or in the side wall. Preferably, the sensor(s) is(are) integrated into the measurement structure on the floor of the receiving device, but sensors can also be provided on or in the side walls of the receiving vessel. For example, conductivity sensors can be arranged on the side walls.
With studies on living cells by means of microtiter plates, a tempering to guarantee the normal living conditions of the cells is problematic. Under certain conditions, moreover, there exists the danger that the cells to be examined can die off on account of lower temperatures, so that the measuring result can then be considerably distorted. In order to avoid this, it is proposed in a refinement of the invention that the microtiter plate or the like have a tempering device on the underside, preferably underneath the measuring structure, which is preferably thermostatically regulable. Exact temperature specifications can thereby be maintained, and studies on thermally sensitive measurement objects are also possible therewith.
In order to be able to record the temperature near the measuring point, at least one temperature measuring sensor, especially a temperature measuring diode, is arranged on the substrate having the measuring structure. In manufacturing the measuring structure, such a temperature measuring sensor, optionally provided at each receptacle, can be produced along with it and thereby be integrated into the measuring structure.
Optionally, the wall thickness of the substrate plate having the sensors and optionally the tempering facility and the like can be,reduced in the area of the individual containers and be dimensioned for a fluoroscopy measurement process. Here, there also exists the possibility for the substrate plate to have at least one transilluminable channel in the area of the individual containers. It is optionally also possible thereby to operate with the previously used fluoroscopy technique, in addition to electrical or electronic measurement.
It is especially beneficial if the semiconductor substrate plate as the measurement structure has at least one field effect transistor, especially an ISFET, whose gate is exposed for contact with the cells. By the direct contact of the gate forming an electrode, a high measurement sensitivity exists. It is advantageous if, in at least one insulated intermediate area of the electrode of the interdigital condenser, an electrochemical-sensitive layer is provided. The sensor is then better suited for detecting certain physiological substances eliminated by the cells, for example oxygen or complex gases. For this, electroactive substances can be placed in the intermediate spaces or be packed in ceramic sponges.
In another embodiment, fiber optics are provided between the electrodes of the interdigital condenser, and for receiving and detecting the light running through the respective fiber optics, light detectors are arranged in the substrate. The measurement facility then makes available additional information, for example about scattered light emitted by the cells, which makes possible an inference on the vitality of the cells. Advantageously, a self test of the measuring facility can consequently be conducted with the aid of the light detectors.
A more exact monitoring of the cells standing in contact with the measurement structures is made possible if CCD sensors, especially in the form of a CCD line or a CCD array, are incorporated into the substrate. An even higher resolution is thereby attained with optical measurement, so that it is also possible, in particular, to monitor morphological changes of individual or several cells arranged in specific areas of the measurement structure.
Expediently, the measurement outputs of the sensors arranged on a common substrate are connected with a control and evaluation facility, in particular integrated on the substrate and in particular connected through a conductor matrix or a network. In the integrated control and evaluation facility, for example, a preprocessing of the measurement values can be undertaken. The evaluation electronics also permits a material and function-specific training of the sensor.
Such an embodiment of the device of the invention can (with appropriate construction of the control and evaluation facility) practically be constructed as an ASIC for microtiter plates, which is adaptable to the most varied measurement objectives and evaluation procedures.